U.S. Pat. No. 6,260,675B1 discloses a magnetic viscous fluid damper installed in a vehicle. The magnetic viscous fluid damper controls the amount of current passed through an electromagnetic coil interposed in a piston to change the strength of a magnetic field generated in the electromagnetic coil, and thereby changes the apparent viscosity of a magnetic viscous fluid.
The electromagnetic coil provided in the magnetic viscous fluid damper is formed with a magnet wire in which one end is connected to the piston and the other end is connected to one electric wire (lead wire). The electric wire is taken, through a rod extending from the piston, out of the damper, and is connected to a controller installed in the vehicle.
A drive current output from the controller is passed through the electric wire to the electromagnetic coil, flows through the electromagnetic coil and is then passed through the piston, the rod, a vehicle body and the like to the negative electrode of a battery.